The identification and quantitation of volatile organic pollutants in air can be challenging, largely because of the complexity of the samples. Analysts may attempt to address this using longer columns and/or slower oven temperature ramps, but this inevitably leads to longer analysis times. However, in recent years, the complexity of such samples has been revealed using comprehensive twodimensional GC (GC×GC).[1]
In this study, we demonstrate how the increased separation capacity of GC×GC techniques provides increased confidence in the identification of compounds in complex air samples, even when using simple detectors, such as flame ionisation detection (FID).
Here, we couple flow-modulated GC×GC–TOF MS/FID with thermal desorption on the UNITY–CIA Advantage-Kori-xr™ system from Markes International. This TD system allows automated trace-level analysis of very volatile VOC and VOCs from canisters, bags and on-line samples, with Kori-xr water management allowing sampling from environments with up to 100% relative humidity.
The cryogen-free operation of the UNITY–CIA Advantage-Kori-xr is complemented by consumable-free flow modulation, which works by filling and flushing a sample loop. This simple operation stands in contrast to thermal modulators, which use a cold zone (usually a jet of nitrogen gas cooled by a chiller unit or liquid nitrogen) to trap and focus analytes, and a hot zone to release the analytes onto the secondary column. This results in additional expense (as well as laboratory space), and in addition the nature of the thermal modulation process makes it incompatible with the most volatile species.
The INSIGHT® flow modulator from SepSolve Analytical uses reverse fill/flush dynamics, meaning that the sample loop is filled in the forward direction from the primary column and then rapidly flushed in the reverse direction onto the secondary column. This ensures breakthrough is eliminated, for sharp and symmetrical peaks for all analytes, including volatiles.
An added advantage of flow modulation is that it enables simple configuration of parallel detection. In this study, both TOF MS and FID data are acquired in a single analysis for confident identification (using reference-quality spectra) and robust quantitation. These detectors are integrated with the other instruments into a single analytical platform with one software interface, and we show how this allows robust, repeatable and affordable GC×GC analysis of hazardous air pollutants.
>> Download the full Application Note as PDF
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